Drill stem protector



United States atent 3,063,760 DRHL STEM PROTECT (DR Bruce M. Gifierd,Houston, Tex, assignor to Plastic Applicators, Inc, a corporation ofTexas Filed June 22, 1959, Ser. No. 821,838 1 Claim. (Cl. S4)

The present invention relates to a drill stem protector.

In the drilling of oil and gas wells, a drilling bit is secured on thelower end of a string of pipe, and as the well bore is progressivelydrilled, additional sections of pipe are added thereto at the surface.Generally speaking, the upper portion of the well bore will be cased, orthat is, the casing will be set in the well bore in the upper partthereof, such casing providing a support for the wall of the well bore.The drill string or drill stem extends downwardly therethrough, and ifthe well bore becomes crooked, or if the drill pipe wobbles duringdrilling, then the drill stem may rub against the casing in the wellbore.

The rubbing of the drill stem against the casing causes undue wearingand scoring of the drill stem as well as the collars which are used toconnect the drill pipe sections together. To overcome this problem,devices termed drill stem protectors have heretofore been provided.

The drill stem protectors presently in use are disadvantageous forseveral reasons. First of all, they are generally formed in a manner sothat the opening through the body of the drill stem protector is muchsmaller than the pipe on which the protector is to fit. Therefore, inorder to position the drill stem protector on the pipe, specialequipment must be used to first expand the protector so that it can beslipped over the collar, and onto the drill string. Not only is itnecessary to use special equipment to position the drill sternprotectors on the drill pipe initially, but it is also necessary toutilize special equipment to try to remove them after they have beenpositioned on the pipe without unduly damaging them.

Additionally, since the longitudinal passage through the drill stemprotector is much smaller than the diameter of the pipe fittingtherethrcugh, stresses are set up in the protector so that when theprotector rubs against the casing in the well bore and cuts or abrasionsare thereby formed in the drill stern protector body, such stressesencourage further splitting and enlarging of the cuts or abrasions.

Additionally, drill stern protectors as presently constructed and used,cause abrasion and damage to the pipe on which they are mounted. Duringdrilling operations a fluid called a mud fluid is circulated downthrough the drill stern and discharged through the drilling bit at thelower end in the well bore. Thereafter such well fluid is circulatedupwardly in the well bore between the drill stem and the well bore walland such fluid includes substances which are quite gritty. When thefluid flows around the protector, some of the fluid flows between theprotector and the drill stem on which the protector is mountednotwithstanding the fact that the drill stern protector is snugly seatedthereon.

If the protector is contaced or urged against the casing in the wellbore while the drill stem is being rotated, some relative rotation mayoccur between the drill stem and the pipe protector. When this happens,the gritty substance in the well bore may gain access to the inside ofthe protector and rub against the surface of the drill stem to score ordamage the drill stem.

Furthermore, the protectors presently in use have been known to slide upover the collar adjacent which they are positioned so that they tend tocollect on one section of the drill string. When this occurs thecirculation of the mud fluid in the well bore is inhibited to such anextent that the well string must be removed from the well bore and thedrill stern protectors repositioned in order that normal drillingoperations may proceed.

The operators of the equipment which install protectors presently usedare service men trained to operate the equipment and additional delayand expense is encountered in bringing the equipment and service men tothe well site which may be located many miles from the nearest availableequipment and service men.

Since the longitudinal passage in the protector is much smaller than thediameter of the pipe on which the protector fits, the protector must becompounded of material which is sufficiently resilient to enable theprotector to be expanded and positioned on the pipe. When the protectoris formed of materials which are sufliciently resilient to allowexpansion for installation, the wear or abrasion resistant qualities ofthe protector are greatly reduced because the materials whichincorporate desirable abrasion characteristics are not suflicientlyresilient to expand in the installation of the protector on the drillpipe.

Therefore drill pipe protectors presently in use tend to wear rapidlyand the nature of the material from which they are formed does notresist abrasion and cutting which will occur when the protector rubsagainst the surrounding casing during drilling operations.

The present invention is directed to a drill stem protector whichovercomes all of the above and other disadvantages of drill stemprotectors presently in use.

An object of the present invention is to provide a drill stern protectorwhich can be readily positioned on a drill stem Without any diflicultyand without any complicated equipment.

Another object of the present invention is to provide a drill stemprotector which can be readily positioned on a drill stem without anydifliculty and without any complicated equipment, by a laborer on thedrilling crew without the assistance of a specially trained service man.

Another object of the present invention is to provide a drill stemprotector which is constructed so that it can be positioned on the drillstem with a minimum of expansion of the protector thereby enabling thedrill stern protector to be formed of substantially non-resilientmaterial having desirable abrasion resistant characteristics.

Yet a further object of the present invention is to provide a drill stemprotector formed of an outer wear-resistant body and a core of solidmaterial engaged therewith and surrounding the drill pipe.

A further object is to provide a protector including an outer body to bepositioned on the drill stern and an inner core which is initiallyliquid but which changes its physical form to a solid to grip the drillstem and anchor the body thereon.

Still a further object of the present invention is to provide a drillstern protector which may be anchored in position on the drill stem toprevent relative longitudinal or rotational movement between the drillstem protector and the drill stern.

Yet a further object of the present invention is to pro vide a drillstem protector and means to anchor the drill stem protector on the drillstem to prevent the flow of drilling fluid between the protector and thedrill stem on which it is seated.

Other objects and advantages of the present invention will become morereadily apparent from the consideration of the following description anddrawings wherein:

FIG. 1 is a diagrammatic View illustrating a drill stem formed of aplurality of sections of drill pipe joined to gether by collars andpositioned in a well bore with drill stem protectors shown in positionon the drill stern;

FIG. 2 is a vertical sectional view of a form of the drill stemprotector of the present invention and showing it positioned on thedrill pipe; and

FIG. 3 is a vertical sectional view of another embodiment of the presentinvention.

Attention is directed to FIG. 1 of the drawings wherein a-well bore isillustrated. at 3 which well bore is provided with a casing extendingtherein as illustrated at 4. The drill stem. is indicated generally bythe numeral 5 and is shown as being formed of a-plurality of sections 6,7 and 8 which are joined together at their adjacent ends by collars 9.

It canbe seen that the drill stem protectors as generally represented bythe numeral 16 are normally positioned one on each section or joint ofpipe, and are generally positioned below the collar 9 on each section ofdrill pipe. When the drill stem 5 is rotated, mud fluid is circulateddownwardlythrough the internal bore 11 thereof and discharged throughthe drilling bit (not shown) in the lower end of the well bore.Thereafter the fiuid is circulated upwardly to the earths surface in theannulus 12 between the drill pipe 5' and the casing 4.

During drilling operations the drill stem 5 may have lateral movementimparted. thereto by either motion of the. drill stem, or by reason ofthe direction in which the well bore 3 is being drilled. When thisoccurs the drill stem 5 moves laterally, and the protectors are providedto act as bushings or bearings to prevent the drill stem 5, or. thecollars 9 thereon, from contacting the casing 4 thereby damaging eitherthe casing 4 or the pipesections, orv collars making up the drill stern.

It will. be noted that the diameter of the drill stem protector 10 islarger than the external diameter of the pipe sections, or the diameterof the drill collars 9 so that the drill stem protectors will contactthe casing and act aswear bushings to prevent wear on the drill stem 5.

It can be appreciated that the general downward movement of the drillstem 5, coupled With the upward flow of drilling fluid in the annulus 12may tend to move the drill stem protectors 10 longitudinally upwardlyalong the drill stem 5 so that heretofore it has not been uncommon forthe drill stem protectors to move over the collars 9 and collect on onesection of the drill stem. When this occurs, the annulus 12 is greatlyreduced in cross-sectional size so that the flow of drilling fluidtherethrough is greatly restricted. Proper circulation of drilling fluidmust be maintained at all times, and heretofore it has been necessaryunder such circumstances to remove the drill string and to repositionthe drill stern protectors on the drill stem.

Additionally, a great deal of ditficulty has been'encountered inpositioning theprotectors of the prior art on the sections of pipe.Also, when the protectors of the prior art contact the casing 4 duringrotation of the. drill stem 5, relative rotation between the protectors10 and the drill stem 5 may occur. This relative rota: tion, coupledwith the circulation of the gritty drilling fluid in the annulus 12hascaused scoring anddamage of the outer periphery of the drill stem onwhichthe protectors of the. prior art have been used.

The protectorsof the present invention overcome all of: these problemsand are illustrated in two embodiments in FIGS. 2 and 3 of the drawings.The drill stem protector of. the present invention includes a tubularbody 21 which may be formed of any suitable material such as rubber or.the like. Under some circumstances the rubber body 21 may be hardened toinhibit Wearthereof, but of course will be softer than the material ofthe casing 4 so that when the protector rubs thereagainst, damage orscoring of the surface of the casing 4 is inhibited.

The tubular body 21 may be provided with round ends as indicated at 22and its outer diameter is larger than the diameter of the pipe section23 on which it is adapted tov be positioned, or the collar 24 whichjoins adjacent pipe sections together.

A passage designated generally at 25 extends concentrically of the body21 and longitudinally therethrough whereby the tubular body 21- may bepositioned on the pipe section 23 of the drill stern. As illustrated inthe drawings, the passage 25 at its end portions 26 and 27 isapproximately the size of the diameter of the pipe section 23 on whichit is adapted to see fit so. as to snugly engage the exterior surface ofthe pipe.

The passage 25 is enlarged between the end portions 26 and 27 thereof todefine a cavity represented generally by the numeral 28. The cavity 28is defined by the annular portions 29 and 30 adjacent the end portions26 and 27 respectively which cavity portions 29 and 30 reduce the volumeof rubber adjacent the end portion 31 of the protector thereby making iteasier to position the protector 2% on the pipe section 23. The cavityportions 29 and 30 also provide an enlarged area adjacent each end ofthe passage 26 and 27 for receiving a plastic mass designated generallyby the numeral 33, which cavity portions 2? and 30 thereby enable alarge deposit of the plastic mass 33 in each end section or portion 31of the body, 21 to aid in anchoring or locking the protector 20 inposition on the pipe section 23.

The cavity 23 is further defined by the enlarged portion designatedgenerally at 35 which extends longitudinally of the tubular body 21, thelongitudinal enlargement or longitudinal cavity portion 35 communicatingwith the annular, radially extending and longitudinally spaced cavityportions 36 in the tubular body 21.

The radial and annular cavity portions 36, by reason of theirlongitudinal spacing, define spaced, annular projections 38 therebetweenas shown in FIG. 2 of the drawings.

It is to be noted that by reason of the above described. construction ofpassage 25, the protector of the present. invention does not grip thepipe section 23 tightly throughout its length and does not set upstresses, or strains in the body 21 throughout the length thereof so as.to encourage splitting of the body when it rubs against; the casingwhich occurs With prior art protectors presently in use. As a matter offact, the major portion of the body 21 is without stress so that thereare no internal forces. in the tubular body 21 which might otherwisetend to rupture or aid in cutting the protector body 21 during use. Anyforces which may exist in the body 21 will be localized adjacent therelatively short ends portions 26 and 27 of the passage 25 where thepassage 25 snugly fits on the pipe section 23.

Since the protector of the present invention does not:

riaLsuch as rubber, so that the constituents thereof incor-.

porate desirable abrasion resistant qualities. This greatly increasesthe life of the protector since it can be formed.

of harder material than heretofore possible which will,

wear longer and will resist wear and abrasion by the drilling fluids andby rubbing against the casing during drilling operations.

The core of the tubular body 21 is formed by the plas-v tic massdesignated generally by the numeral 33 which plastic mass fills thecavity 28 including the portions 29, 3t), 35 and 36 thereof, all ofwhich surround the pipe section 23. The plastic mass 33 may be anysuitable material which is initially in liquid form when poured in thebody 21, and which will harden after a relatively short period of time.

For example, the plastic mass may be an epoxy or phenolic type resinwhich incorporates a catalyst therein to aid in changing the mass fromits original liquid form, to solid form. Generally speaking, the plasticmass 33. may be any material the physical form of which is origi nallyliquid, and which physical form may be changed to. a solid by chemicalreaction. It may even be of any suitable plastic material which hardensafter a period of time such as cement or the like. The plastic mass maybe insertcd. in the body through a passage 40. in the body 21 by anysuitable means such as the syringe tool 41 shown in FIG. 2 of thedrawings as being inserted in the passage 40 and squeezed manually toforce the plastic mass 33 into the cavity 28.

It will be noted that the plastic mass 33 when it fills the cavity 23completely surrounds the pipe section 23 and after the plastic mass 33has hardened serves to anchor the tubular body 21 on the pipe section23.

Since the cavity 28 extends substantially throughout the length of thetubular body 21, with the exception of the end portions 26 and 27 of thepassage 25, it can be appreciated that a substantial surface area of thepipe is exposed to the plastic mass 33, whereby the plastic mass 33 maybond with the surface of the pipe 23 over a substantially large area ofthe pipe 23 when the plastic mass 33 hardens. Additionally, since theplastic mass 33 contacts the surface of the pipe section 23substantially throughout the area of the tubular body 21 of theprotector, it can be seen that entry of drilling fluid between the pipeprotector 2t and the pipe section 23 is prevented.

Also, since the plastic mass 33 bonds to the surface of the pipe section23, and is also anchored in the body 21, the tubular body 21 of theprotector 26 is thereby firmly anchored or held in position on the drillstem, thereby requiring an unusual longitudinal force before anymovement of the pipe protector 2i longitudinally of the drill stem canoccur. This is extremely advantageous in that when the drill stemprotectors have been positioned on the drill stem, they will retaintheir position throughout the drilling operation.

The annular radially extending cavities 36 which define the projections38 provide an arrangement so that when the plastic mass 33 is injectedinto the cavity 28 to fill the cavities 36 the projections 38 form atongue and groove connection therewith to aid in locking the plasticmass 33 as a core in the tubular body 21. This anchors the plastic core33 and surrounding body 21 together firmly and prevents relativemovement and separation of the plastic core 33 from the body 21 duringdrilling.

In this regard it will be seen that the projections 38 defined by thecavities 36 are dove-tailed in shape so that their inner ends 43 arecloser together than their outer ends 44. It will be appreciated thatthis construction enables the core or plastic mass 33 to be firmlylocked or retained in position in the tubular body 21.

In FIG. 3 another form of the drill stem protector is illustratedwherein the cavity 28 is formed in a slightly difierent manner.

In FIG. 3 it will be noted that the annular radial cavities 36' arelongitudinally spaced to define the projections 38' therebetween. InFIG. 3 the cavities 36 are defined by the surface portions 36a and 36bwhich are substantially parallel to each other to provide a cavityportion 36 of slightly difierent configuration.

From the above description it can be appreciated that when the body 21is positioned on the section 23 of the drill stem, it is not under anytension. The plastic mass 33 can be injected into the cavity 28 untilsome of it seeps out as illustrated at 46 in FIG. 2 to indicate that thecavity 28 is completely filled.

Tests have indicated that two to three times as much longitudinal forceis required to move the protector of the present invention thannecessary to move protectors of the prior art.

It is desirable, of course, that the plastic mass 33 be of a suitableform so that if and when desired to remove the protectors 29 from thedrill stem, the plastic mass 33 will not leave any undesirable mass ormaterial thereon.

Such the diameter of the passage 25 is substantially the diameter of thepipe 23 on which the protector 20 is positioned only adjacent theportions 26 and 27, it can be appreciated that the protector need onlybe flexed adjacent the endportions 26 and 27 to insert or to pass itover the collar 24:. Thus, no special equipment or tools are necessaryto position the protector of the present invention on the pipe section.

Additionally, while it is necessary with prior art protectors toposition them adjacent and below a collar as illustrated in FIG. 1 ofthe drawings, it can be appreciated that the protector of the presentinvention may be positioned at any point on the pipe section 23.

Broadly the present invention relates to a pipe protector, and moreparticularly to a pipe protector having an outer body to form a bushing,and an inner core to seal off between the outer body and the pipe onwhich the protector is seated.

What is claimed is:

A drill stem protector adapted to be positioned on a drill stem forprotecting the drill stem and the collar connecting the sections ofdrill stern together comprising, a one-piece tubular body having anouter diameter of greater extent than the diameter of the drill stem andcollars thereon on which said tubular body is to be positioned, apassage concentric with the longitudinal axis of said body, the diameterof said passage being less than the diameter of the drill stern collarson which said tubular body is to be positioned, said passage beingenlarged between the ends of said body to form a cavity for surroundingthe drill stem when said tubular body has been positioned thereon, and aplastic mass within and filling said cavity which is initially a liquidbut which chemcally reacts to change to a solid upon setting to bondsaid protector body to the drill stern on which said tubular body hasbeen positioned, a plurality of annular flanges formed integrally withsaid body and spaced longitudinally in said cavity to aid in bondingsaid body with said plastic mass, said cavity extending substantiallythe longitudinal extent of said body but terminating short of the endsof said body to define relatively short annular end portions on saidbody which are substantially the same size as the drill stem on whichsaid body is positioned to snugly engage the exterior surface of saiddrill stem.

References Cited in the file of this patent UNITED STATES PATENTS RubberWorld, April 1954, pages 66 through 69 relied upon.

